Process of preparing



Patented Sept. 3, 1957 5, i The process of our invention is illustratedby the fol lowing equations: PROCESS OF PREPARING 1,3,5-TRIAZ]NE-2,4,6OK

TRICARBOXYLIC ACID 7 Christoph J. Grundmann and Ehrenfried Kober, Colum-5 N5 0 bus, Ohio, assignors to Olin Mathieson Chemical Coro poration, acorporation of Virginia \1/ No Drawing. Application September 18, 1956,N

Serial No. 610,635 0 G1 6 Claims. ((11.260-248) 10 4\ Our inventionrelates to the preparation of high purity, (:10 o-de 2 i 0001 K31: 1,3,5triazine 2,4,6 tricarboxylic acid and its chlo- E ride salt by means ofsimple and novel reactions. (II) It is known that esters of cyanoformicacid can be C COG1 readily polymerized to the corresponding esters of1,3,5- f' 3N triazine 2,4,6 tricarboxylic acid: n +3HCOOH C-COOR CIOC- 62C-COC1 %4\ 3NCCOOR N5 31H N n0oods zo-ooon (11) N5 3N wherein R ismethyl or ethyl, for example. Treatment H000All; g 3HC1+300 of theseesters with aqueous potassium hydroxide leads \1/ to the correspondingtri-potassium salt, N

: 7 (III) 0-0001: According to our invention, the 1,3,5-triazine-2,4,6-tricarboxylic acid chloride is made by slowly adding the KOOCC61/2C O0OKalkali metal salt, e. g. the potassium salt, of 1,3,5-triazine- 2,4,6tricarboxylic acid to phosphoryl chloride. Pref- Title use of"hydroxictlies of tltile other alkaliimetalls, e. igi tlg gltlgliletilgztpggcfefitpaltggpgiggrg0 g so rum or 1 111m, pro uces t ecorrespon ing sa ts. t is reported that the free acid cannot be obtainedfrom the as about however After reacton potassium salt. Gentle warmingof aqueous solutions of g g g g g 1S fi at the potassium salt producesammonia indicating the strong 35 2 t i j a tendency of this compound toundergo hydrolytic cleavage fiepara e y g ifi i or ii? 6 resulting incomplete destruction of the molecule. Alter- Orgamc so ven Suc y e feenatively, a cold aqueous solution of the potassium salt 2 g thfen P i gadmlxmglthe chonde owlth can be acidified with dilute mineral acids.However, an Y mus m? Prefera at 3 out 0 to 30 of e ree triazlne tricarox 1c acl to a sor t e 1nor anic Salts f d The inozganic Salt, f examplepotasiium not be heated because of undesirable side reactions whichchloride if dilute hydrochloric acid is used on the potastend to P Yleldand f l y 0f the trlaZlIle sium salt of the triazine tricarboxyhc acid,cannot be recarboxyllc The reactlon therefore, allowed to moved byleaching the product with Water or other 1 go to completion at roomtemperature for about 12 to 60 tive solvents. Furthermore, such crudeacid as is formed hours' by this method also contains organic impuritiesSuch as The following examples further illustrate our process.logifiiigngnd cyanuric acids, resulting from side hydrolytic Example I Aknown route for the preparation of 1,3,5-triazine- The potassium salt of1,3,5 triazine 2,4,6 tricar- 2,4,6-tricarboxylic acid chloride involvesreaction of its bonic acid was slowly added to 160 grams of phosphorylethyl ester with phosphorus pentachloride to form the chloride withstirring. At the end of 10 minutes a total tricarbonic acid chloride.This method produces a very of 37 grams of the salt had been added andthe temperaimpure oil whose complete purification is very difiicult turewithin the reaction flask rose to 70 C. When the and uneconomical.spontaneous reaction stopped, the mixture was refluxed We have foundthat 1,3,5 triazine 2,4,6 tricarat 104 C. for 2 hours. After cooling themixture, it boxylic acid chloride (11) can be readily prepared by rewasextracted with three 100 milliliter portions of anhyacting an alkalimetal Salt 0f a drous ether. The three extracts were combined anddisboxylic acid (I) with phosphoryl chloride. The recovtilled. The 1,3,5triazine 2,4,6 tricarboxylic acid cry of the pure acid chloride iseasily accomplished by chloride came over, after the ether and excessphosphoryl extraction and subsequent removal of the extractant bychloride, at 114-115 C. and 0.2 millimeter, as a slightdistillation- Wehave also found that 0111 high P y 13' yellow liquid. Upon standing theproduct crystallized acid chloride can be reacted with formic acid toform to i 21,8 grams, or 73 percent f th the y, f

a high p y 1.3.5-triazine-2.4.6tricarboxylic acid D- crystals whichmelted at 54.556 c. and whose re- This reaction cannot be accomplishedby hydrolysis, as

normally expected. Hydrolysis does not yield the free acid, but2,4,6-trihydroxy-1,3,5-triazine is formed. The ease of separation of thefree triazine tricarooxylic acid from the reaction mixture is anotheradvantage peculiar fractive index was 11. 1.647.

G 26, 5 39. 3 15.66 to our reaction. The by-products are all gaseous andgififi kNaOl 3 8 15.89 the product is insoluble in formic acid. Initialseparation 27.00 39- 60 15.89

is attained by decantation or by means of filtration.

3 a Example II While stirring 50 grams of anhydrous formic acid at C.,14.4 grams of the 1,3,5-triazine-2,4,6-tricarboxylic acid chloride wasadded, dropwise, thereto.

The stirring was continued for 14 hours atroom temperature during whichtime hydrogen chlorideand carbon monoxide were evolved and awhite-precipitate of 1,3,5 triazine 2,4,6 tricarboxylic acid formed.After allowing the mixture to stand for two more days at roomtemperature, the free acid was separated by s'ucti'ori fik tration,washed with ether and dried in vacuo over potassium hydroxide. Finalpurification was accomplished by Soxhlet extraction with ether for 48hours. The yield was 9.4 grams, 82 percent of the theory, of odorless,white crystals which decomposed between 160 and 350 C. without melting.

The hydrogen values are high because the product cannot be completelydehydrated by drying below its decomposition temperature.

We claim: I

1. A method of preparing 1,3,5 triazine 2,4,6 tricarboxylic acid whichcomprises admixing an alkali metal salt of 1,3,5 triazine 2,4,6tricarboxylic acid 4 with phosphoryl chloride to form 1,3,5 triazine2,4,6- tricarboxylic acid chloride and admixing said acid chloride withformic acid.

2. A method of preparing 1,3,5 triazine 2,4,6- tricarboxylic acid whichcomprises admixing an alkali metal salt of 1,3,5 triazine 2,4,6tricarboxylic acid with phosphoryl chloride at a temperature of about 10to 100 C. to form 1,3,5 tr'iazine 2,4,6 tricarboxylic acid chloride andadmixing said acid chloride with formic acid at a temperature of about 0to 30 C.

3. A method of preparing 1,3,5 triazine 2,4,6- tricarboxylic acidchloride which comprises admixing an alkali metal salt of 1,3,5 triazine2,4,6 -tricarboxylic acid with phosphoryl chloride.

4. A method of preparing 1,3,5 triazine 2,4,6- tricarboxylic acidchloride which comprises admixing an alkali metal salt of 1,3,5tria-zine 2,4,6 tricarboxylic acid with phosphoryl chloride at atemperature ofabout 1-05 to 100 c. v

5. A- method of preparing 1,3,5 triazine 2,4,6- tricarboxylic acid whichcomprises admixing 1,3,5 tria-' zine 2,4,6 tricarboxylic acid chloridewith formic acid.

6. A method of preparing. 1,3,5 triazin'e' 2,4,6- tricarboxylic acid"which comprises admixing 1,3,5 triazine 2,4,6 tricarboxylic acidchloride with formic acid at a temperature of about 0 to C.-

No references cited.

1. A METHOD OF PREPARING 1,3,5 -TRIAZINE - 2,4,6 - TRICARBOXYLIC ACIDWHICH COMPRISING ADMIXING AN ALKALI METAL SALT OF 1,3,5 -TRIAZINE -2,4,6 -TRICARBOXYLIC ACID WITH PHOSPHORYL CHLORIDE TO FORM 1,3,5 -TRIAZINE - 2,4,6TRICARBOXYLIC ACID CHLORIDE AND ADMIXING SAID ACIDCHLORIDE WITH FORMIC ACID.